Previously known from Finnish patent 12457 is edge cutting by a water jet. From the Finnish publications 83106 and 88417 diagonal cutting of a paper web is known, i.e. in the first place longitudinal cut off by means of a water jet.
The construction as per patent 12457 can be applied when the paper web speed is slow and cutting carried out close to the wet end. Then the forces generated by cutting hardly have an impact on the web forward travel. Instead, cutting of dry paper has turned out to be difficult by growing web speeds. Especially, on coating the paper, the edge arrives at cutting only after coating, where the uneven edge margin with the coating border is removed. After coating, due to cutting, the advancing web is equal in quality up to the edge. It has been established that a high-speed water jet produces in the edge of a fast moving web braking powers preventing the use of a water jet cutter. The web proceeds indeterminately and the possibility of breaks in the line grows.